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Old 27th Dec 2019, 8:35 pm   #1
angusb1
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Default Ferguson Radiogram 387RG Favourite II

Hi All,

This is my first post here. I found the forum while I was looking for information about my Grandad's radiogram which I inherited from him a few years ago. I've read all the posts I could find which reference this model and the stickies on this forum and I could do with some advice about if I should replace the capacitors (and if so which ones) which I understand is often needed on this kind of model. From reading Darren-UK's sticky on capacitor replacement I thought that the capacitors in my device don't seem to be the waxed paper kind, but there are some Hunts Mouldseal ones and some that look like the small tubular ones. Please could anyone confirm this and whether I need to replace them?

Before I read up on all this I did briefly power up the set and could get AM radio fine, but no FM.

I also thought you might find some photos useful and interesting.

I have managed to find "Trader" Service Sheet 1299 from 4th May 1957 which has circuit diagrams and covers the similar 385RG amongst others. If you can tell me the capacitors from that which need replacing I can work out which ones they are on my device.

Thanks for any help you can give me.

Angus
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Old 27th Dec 2019, 10:45 pm   #2
music-centre
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Default Re: Ferguson Radiogram 387RG Favourite II

Hello Angus,
I don't have a diagram but the only ones from the pictures which would be worth changing as being likely to be faulty are those few Hunts Mouldseals and the Plessey Electrolytic one with the red/black ends.
If after that there is no FM, personally I would try swapping the ECC85 Valve.
Steve.
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Old 27th Dec 2019, 10:57 pm   #3
paulsherwin
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Default Re: Ferguson Radiogram 387RG Favourite II

The components that have stripes on them but that are not resistors are ceramic capacitors. Manufacturers started to switch from waxies to ceramics in the late 50s and used them until cheap plastic film types became available about 5 years later. Ceramics don't fail very often and don't need changing in the absence of a fault.

The Mouldseals are likely to be bad.

Have you cleaned the wavechange switch carefully? Many AM/FM valve sets spent their working lives tuned to the Home Service or Light Programme on AM, and the FM contacts oxidised badly.

What aerial are you using for FM?
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Old 28th Dec 2019, 5:01 pm   #4
angusb1
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Default Re: Ferguson Radiogram 387RG Favourite II

Quote:
Originally Posted by music-centre View Post
Hello Angus,
I don't have a diagram but the only ones from the pictures which would be worth changing as being likely to be faulty are those few Hunts Mouldseals and the Plessey Electrolytic one with the red/black ends.
If after that there is no FM, personally I would try swapping the ECC85 Valve.
Steve.
Thanks Steve. I will get the electronics of it out and swap those capacitors.

Quote:
Originally Posted by paulsherwin View Post
The components that have stripes on them but that are not resistors are ceramic capacitors. Manufacturers started to switch from waxies to ceramics in the late 50s and used them until cheap plastic film types became available about 5 years later. Ceramics don't fail very often and don't need changing in the absence of a fault.

The Mouldseals are likely to be bad.

Have you cleaned the wavechange switch carefully? Many AM/FM valve sets spent their working lives tuned to the Home Service or Light Programme on AM, and the FM contacts oxidised badly.

What aerial are you using for FM?
Thanks Paul. I will take out the electronics and replace the moundseals, and while I'm at it I will see if I can clean the contacts on the wavechange switch. The FM aerial it is using is a wire which runs across the back of the shelf which all the electronics sit on. It is just a piece of insulated wire which has been in place for ever but I could try plugging in a different aerial, it would be simple and cheap to try.
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Old 28th Dec 2019, 9:03 pm   #5
PortugalTV
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Default Re: Ferguson Radiogram 387RG Favourite II

be extra carefull with the soldering iron around the transparent polistyrene capacitors...if you melt them or heat them even slghtly its and instant short..i see two of those on the first pic...they never fail if left alone.

like others have said replace the hunts caps and that nasty plessey electrolitic then i advise to swap the ecc85 and clean the switching if the fm is dead
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Old 29th Dec 2019, 4:04 am   #6
TonyDuell
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Default Re: Ferguson Radiogram 387RG Favourite II

Quote:
Originally Posted by PortugalTV View Post
be extra carefull with the soldering iron around the transparent polistyrene capacitors...if you melt them or heat them even slghtly its and instant short..i see two of those on the first pic...they never fail if left alone.
That's what I used to think. And then I had a polystyrene capacitor that did a good impression of a randomly changing resistor (around 10k IIRC) in the filter section of an HP telephone line analyser. Took a long time for me to track that one down as I didn't suspect the capacitors...

So yes, they are generally reliable and not 'change on sight' but they can fail.
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Old 29th Dec 2019, 9:46 am   #7
'LIVEWIRE?'
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Default Re: Ferguson Radiogram 387RG Favourite II

I, too, know that polystyrene capacitors can occasionally fail. Back in the early 70s a range of Radiomobile Car Radios used a Colpitts Oscillator circuit featuring two polystyrene caps (4700pf & 1100pf, IIRC) Sometimes one of these would do a good impression of a resistor!
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